Minimally-invasive interventions are performed in order to treat diseases of the heart or other hollow organs, by inserting a medical instrument, for instance a catheter or an ablation catheter, into the organ to be treated. In this way, an ablation catheter can be inserted into the atrium by way of intravenous access, where it thermally cuts interfering nerve conduction paths in two by means of high-frequency energy. The prerequisite for this therapy is however that the ablation catheter is moved to precisely the right point and that the intervention is monitored using an imaging method.
An apparatus for navigating a medical instrument is known from US 2003/0137380 A1. Two special rotatable and pivotable permanent magnets are used there on the left and right side of the patient bed at the level of the heart region, said permanent magnets lying opposite one another. The intervention is monitored here using an imaging apparatus, like an x-ray device for instance. An x-ray source and an x-ray detector are arranged here opposite one another and generate fluoroscopy images of the patient during the magnetic navigation of a guide wire or catheter. With the apparatus known from US 2003/0137380 A1, the two magnets for generating the magnetic field are located on the right and left of the patient, who is lying on a patient support table. This apparatus is disadvantageous in that patient accessibility is poor, and at the same time the heavy and bulky permanent magnets result in high installation costs.